Biomedical subjects

Ken Watanabe

Publications and source records attributed to Ken Watanabe.

44 records · Page 3Linked to original sources

PubMed2002

A RING finger protein Praja1 regulates Dlx5-dependent transcription through its ubiquitin ligase activity for the Dlx/Msx-interacting MAGE/Necdin family protein, Dlxin-1.

Msx2 and Dlx5 are homeodomain proteins that play an important role in osteoblast differentiation and whose expression is induced by bone morphogenetic proteins. Recently we have identified a novel protein, Dlxin-1, that associates with these homeodomain proteins and regulates Dlx5-dependent transcriptional function (Masuda, Y., Sasaki, A., Shibuya, H., Ueno, N., Ikeda, K., and Watanabe, K. (2001) J. Biol. Chem. 276, 5331-5338). In an attempt to elucidate the molecular function of Dlxin-1, two closely related RING finger proteins, Praja1 and Neurodap-1, were isolated by yeast two-hybrid screening using the C-terminal necdin homology domain of Dlxin-1 as bait. Glutathione S-transferase pull-down and immunoprecipitation/Western blotting assays following co-transfection of Dlxin-1 and Praja1 revealed that Praja1 binds to the C-terminal necdin homology domain of Dlxin-1 in vitro and in vivo, respectively. Overexpression of Praja1 caused a decrease in Dlxin-1 protein level, which was reversed when a proteasome inhibitor was added. Overexpression of Praja1 with a mutation in the RING finger inhibited the decrease in Dlxin-1 protein, pointing to the importance of ubiquitin-protein isopeptide ligase (E3) activity associated with RING finger. Wild-type Praja1, but not its RING finger mutant, promoted ubiquitination of Dlxin-1 in vivo. Finally, expression of Praja1 down-regulated Dlx5-dependent transcriptional activity in a GAL4-dependent assay. These results suggest that Praja1 regulates the transcription function of the homeodomain protein Dlx5 by controlling the stability of Dlxin-1 via an ubiquitin-dependent degradation pathway.

Antigens, Neoplasm↗

PubMed2002

Doppler echocardiographic differentiation of functional from anatomical pulmonary atresia: analysis using quantitative parameters.

Functional pulmonary atresia must be distinguished from anatomical atresia, which has an intact ventricular septum, to avoid inappropriate treatment, but there is a paucity of data regarding the echocardiographic features that differentiate these conditions. Echocardiographic findings in 5 neonates with functional atresia were compared to those in 5 with anatomical atresia. The left and right ventricular end-diastolic dimensions (LVDd, RVDd), percent of normal predicted LVDd, RVDd/LVDd, tricuspid valve ring diameter (TVD), percent of normal predicted TVD, grade of tricuspid regurgitation (TR), peak TR velocity, pulmonary valve ring diameter (PVD), percent of normal predicted PVD, the minimum diameter of the ductus and the peak velocity through it (PDA velocity) were measured. In addition, systolic pulmonary (PAp) and right ventricular pressure (RVp) from either PDA velocity or TR velocity, and calculated PAp/RVp were also estimated. There were significant differences in RVDd/LVDd, %TVD, and peak TR velocity between the 2 groups. All functional patients showed RVDd/LVDd >0.6, %TVD >100%, estimated RVp <50mmHg, PAp/RVp >0.85, and peak TR velocity <4m/s, whereas the findings in anatomical atresia patients were completely the opposite. In conclusion, a large RVDd/LVDd, TVD, PAp/RVp, low RVp and small TR velocity all suggest functional rather than anatomical pulmonary atresia, although there may be some exceptions such as severe Ebstein anomaly.

Diagnosis, Differential↗

PubMed2002

Vitamin D hormone inhibits osteoclastogenesis in vivo by decreasing the pool of osteoclast precursors in bone marrow.

Previous observations that vitamin D hormone induces the expression of the receptor activator of nuclear factor kappaB (NF-kappaB) ligand (RANKL), thereby stimulating osteoclastogenesis in vitro, led to the widespread belief that 1alpha,25-dihydroxyvitamin D3 [1a,25(OH)2D3] is a bone-resorbing hormone. Here, we show that alfacalcidol, a prodrug metabolized to 1alpha,25(OH)2D3, suppresses bone resorption at pharmacologic doses that maintain normocalcemia in an ovariectomized (OVX) mouse model of osteoporosis. Treatment of OVX mice with pharmacologic doses of alfacalcidol does not increase RANKL expression, whereas toxic doses that cause hypercalcemia markedly reduce the expression of RANKL. When bone marrow (BM) cells from OVX mice were cultured with sufficient amounts of macrophage colony-stimulating factor (M-CSF) and RANKL, osteoclastogenic activity was higher than in sham mice. Marrow cultures from alfacalcidol- or estrogen-treated OVX mice showed significantly less osteoclastogenic potential compared with those from vehicle-treated OVX mice, suggesting that the pool of osteoclast progenitors in the marrow of vitamin D-treated mice as well as estrogen-treated mice was decreased. Frequency analysis showed that the number of osteoclast progenitors in bone marrow was increased by OVX and decreased by in vivo treatment with alfacalcidol or estrogen. We conclude that the pharmacologic action of active vitamin D in vivo is to decrease the pool of osteoclast progenitors in BM, thereby inhibiting bone resorption. Because of its unusual activity of maintaining bone formation while suppressing bone resorption, in contrast to estrogens that depress both processes, vitamin D hormone and its bone-selective analogs may be useful for the management of osteoporosis.

Animals↗

PubMed2002

Role of inducible nitric oxide synthase in skeletal adaptation to acute increases in mechanical loading.

To clarify the role of nitric oxide (NO) in regulation of bone metabolism in response to skeletal loading, we examined inducible NO synthase (iNOS) gene knockout mice in the tail-suspension model. Histomorphometric analyses of proximal tibias revealed that 7 days of tail suspension decreased the bone volume (BV/TV) and bone formation rate (BFR/BS) and increased the osteoclast surface (Oc.S/BS) in mice with all iNOS genotypes. Both iNOS+/+ and iNOS+/- mice responded to subsequent 14-day reloading, with increases in BV/TV and BFR/BS and a decrease in Oc.S/BS, whereas these responses were abolished in iNOS-/- mice. The osteoblasts flattened after tail suspension appeared cuboidal during subsequent reloading. Immunoreactivity for iNOS was detected in these osteoblasts and osteocytes by immunohistochemistry. These defective responses after reloading were rescued in iNOS-/- mice by treatment with an NO donor nitroglycerine (NG). Conversely, the responses in iNOS+/+ mice were inhibited by treatment with an NOS inhibitor aminoguanidine (AG). In bone marrow cell cultures, mineralized nodules derived from iNOS-/- mice after reloading were significantly reduced. Taken together, our results suggest that NO generated by iNOS in osteoblasts plays a critical role in adjusting bone turnover and increasing osteogenic activity in response to the acute increase in mechanical loading after tail suspension.

Adaptation, Physiological↗

PubMedDate not supplied

Functional aortic stenosis diagnosed in fetal period.

We report a case of fetal congenital heart disease prenatally diagnosed as critical aortic valve stenosis at 25 weeks of gestation. Fetal echocardiography demonstrated severe mitral regurgitation, aortic valve stenosis, hypocontractility of the left ventricle, and showed retrograde flow in the aortic arch like HLHS (hypoplastic left heart syndrome). However, soon after delivery, improvement in the baby's hemodynamics and myocardial contractility were recognized without any treatment.

Adult↗

PubMedDate not supplied

Prenatal diagnosis of congenitally corrected transposition of the great arteries. A case report.

Congenitally corrected transposition of the great arteries (CTGA) is an uncommon congenital cardiac anomaly. Prenatal sonographic diagnosis of CTGA is very difficult because the ventricular outflow tract may appear to arise correctly from the right and left ventricles. Few cases of CTGA diagnosed in utero have been reported. We report a case of CTGA with complete heart block, ventricular septal defect and pulmonary valve stenosis diagnosed at 30 weeks' gestation after the mother was referred to our hospital because of persistent fetal bradycardia.

Echocardiography↗

PubMedDate not supplied

Morning glory systemically accumulates scopoletin and scopolin after interaction with Fusarium oxysporum.

An isolate of non-pathogenic Fusarium, Fusarium oxysporum 101-2 (NPF), induces resistance in the cuttings of morning glory against Fusarium wilt caused by F. oxysporum f. sp. batatas O-17 (PF). The effect of NPF on phenylpropanoid metabolism in morning glory cuttings was studied. It was found that morning glory tissues responded to treatment with NPF bud-cell suspension (108 bud-cells/ml) with the activation of phenylalanine ammonia-lyase (PAL). PAL activity was induced faster and greater in the NPF-treated cuttings compared to cuttings of a distilled water control. High performance liquid chromatography analysis of the extract from tissues of morning glory cuttings after NPF treatment showed a quicker induction of scopoletin and scopolin synthesis than that seen in the control cuttings. PF also the induced synthesis of these compounds at 10(5) bud-cells/ml, but inhibited it at 10(8) bud-cells/ml. Possibly PF produced constituent(s) that elicited the inhibitory effect on induction of the resistance reaction. These compounds could potentially be useful as markers to detect early beginning interactions between Fusarium and morning glory tissues cuttings.

Coumarins↗

PubMedDate not supplied

Phytotoxic components produced by pathogenic Fusarium against morning glory.

A pathogenic isolate of Fusarium, F. oxysporum f. sp. batatas O-17 (PF), causes wilt disease in leaf etiolation in sweet potato (Ipomoea batatas) and morning glory (Ipomoea tricolor). Extracts from PF cultures were screened for phytotoxic components using a growth inhibition assay with morning glory seedlings. The extracts were fractionated using differential solvent extraction and two active compounds, ergosterol and fusalanipyrone, were isolated from the less-polar fraction. Growth inhibition of morning glory seedlings showed a sigmoidal dose-response relationship, with fusalanipyrone exhibiting a two order of magnitude higher EC50 value than ergosterol (18 nM and 1.6 microM, respectively). Both compounds showed lower growth inhibition activity towards lettuce seedlings (Lactuca sativa). This study provides information on the phytotoxic components of PF and discusses the mechanism behind PFf-induced phytotoxicity.

Ergosterol↗